ASCIISubSequence.java

import java.util.ArrayList;

public class ASCIISubSequence {
    public static void main(String[] args) {
  Ascii("", "abc");
  System.out.println(AsciiArr("", "abc"));
    }

    //using void function
    static void Ascii(String p,String up){
        if(up.isEmpty()){
            System.out.println(p);
        return;
        }
        char ch=up.charAt(0);
        Ascii(p+ch, up.substring(1));
        Ascii(p, up.substring(1));
        Ascii(p+(ch+0), up.substring(1));


    }

    //using ArrayList 

    static ArrayList<String> AsciiArr(String p,String up){
        if(up.isEmpty()){
            ArrayList<String> list=new ArrayList<>();
            list.add(p);
            return list;
        }
        char ch=up.charAt(0);
        ArrayList<String> first= AsciiArr(p+ch, up.substring(1));
        ArrayList<String> second= AsciiArr(p, up.substring(1));
        ArrayList<String> third= AsciiArr(p+(ch+0), up.substring(1));
first.addAll(second);
first.addAll(third);
return first;
    }

}